OK, add reinterpret_pointer_cast (I don't see why not, we need reinterpret_pointer_cast for the same reasons we need reinterpret_cast) to my request list, but the aliasing request is different: it doesn't simply treat a shared_ptr<T> as a shared_ptr<Y>. What I need is a shared_ptr constructor, which takes a shared_ptr and a raw pointer, and returns a shared_ptr of the type of the raw pointer which points the same object the raw pointer points, but shares ownership (the "pn" member of shared_ptr) with the original shared_ptr: template <class T> shared_ptr { .... template <class Y> shared_ptr( shared_ptr<Y> const & sp, T * p ): px(p), pn(sp.pn) { } .... }; It may be a good idea to make this constructor private, and to call it from a friend namespace-scope function with a name which clearly indicates what's going on: template <class T,class Y> shared_ptr<T> some_really_descriptive_name( shared_ptr<Y> const & sp, T * p ); --Emil Dotchevski ----- Original Message ----- From: "Joe Gottman" <jgottman@carolina.rr.com> To: <boost@lists.boost.org> Sent: Wednesday, October 25, 2006 5:06 PM Subject: Re: [boost] shared_ptr feature request
"Emil Dotchevski" <emildotchevski@hotmail.com> wrote in message news:BAY102-DAV10CB89F05952821C9EE4CBD4060@phx.gbl...
I think it would be useful to add the following features to shared_ptr:
1. Support for aliasing: if I have a shared_ptr<T> pt, to get a shared_ptr<Y> py (where T and Y are possibly unrelated types) such that pt and py share ownership. For example, if T is an array of elements of type Y, with this feature pointing an element from the array through a shared_ptr<Y> would keep the entire array afloat. Similar example is being able to point through a shared_ptr<Y> to a member of an object of class T, which would keep the entire T object afloat.
We currently have static_pointer_cast, dynamic_pointer_cast, and const_pointer_cast, which, naturally enough, perform static_cast, dynamic_cast, and const_cast on the underlying pointer. What you are asking for is basically a reinterpret_pointer_cast. If you can give a use case it seems natural enough.
Joe Gottman
_______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost